Oliver James: The caught jester

A friend recently wrote off an ex-boyfriend with the words 'I think he's got a personality disorder' (hence-forth PD). Increasingly, I suspect this diagnosis is used colloquially as a way of sticking disliked people in the dustbin, but how many of us really know what the term means?

Strictly speaking, four main criteria are employed by psychiatrists when making the diagnosis. The first is an abnormal pattern of emotion, such as feeling things more keenly than usual, febrile mood shifts and spectacular, unpredictable rages. Then come abnormal thoughts, downright weird ideas - like delusions of grandeur or paranoid attributions of motive. Next, there are unstable or unusual relationships and a tendency to dip in and out of friendships. Finally, there is impulsiveness, novelty-seeking, a short attention span.

Put crudely, you know you're in the company of someone with a PD if they are a 'me, me, me' egotist who becomes restless if the conversation does not put them at its centre. They may be prone to wildly unrealistic notions of what they can achieve, omnipotently self-deceiving. They go in for massive denial of uncomfortable facts and project into you what they are really thinking - you often leave their presence full of the shit that they can't tolerate. They may be superb impersonators, have several very different selves (known as sub-personalities) and be able to suddenly seem as if they are not there, emotionally ('Me, I disconnect from you').

Because people like this very often also have other mental illnesses, they can be hard to differentiate. Half of the most common kind (Borderline PD) also suffer depression and paranoia, while two-thirds of criminals have Antisocial PD. People with PD are also much more likely to have affairs.

It's confusing that most of us have some of these symptoms, sometimes. But while many people are game-players when at work, or at play, people with PD live their lives as if they are actually playing those roles, and are able to switch between personae with perplexing ease. In many respects they resemble adolescents. They also treat others with a callous lack of empathy. Many people with PD are very charming and highly entertaining, but this charm is liable to be employed in order to people-please or to manipulate. When you get to know them better, their playfulness emerges as a restless struggle to feel alive. At their core is a weak sense of self and an existential deadness.

Having interviewed 70 or so famous high achievers, I would say that very few did not have PD. Becoming The Best, The Richest or The Most Famous is one way to compensate for their lack of identity and feelings of worthlessness. Alas, it doesn't work. Whether successful or unsuccessful, unless they get some first-class psychoanalytic treatment, the person with PD is still lumbered with the same problems: who am I? Why am I such a worthless, powerless worm?

The mental block

Is one age group more susceptible to nostalgic advertising than others?

A study in Psychology and Marketing reveals that nostalgia in adverts works only for specific product types that evoke specific memory periods from one's youth - and that there are big gender differences.

The study's consumers, aged 16 to 88, only felt nostalgic if a song was from their late teens and early twenties. Liking for film stars peaked at 14, and for Oscar-winning movies at 27. Surprisingly, fashion-model styles evoked nostalgia in men only, not women.

Men who are not nostalgic, and nearly all women, do not prefer cars from their youth, leading the authors to suggest that the catchline 'It's not your father's Oldsmobile' (or in this country, Ford Cortina) is more likely to work with them. By contrast, among nostalgic men, the new VW Beetle and Mini Cooper prove the enduring power for Baby-boomer men (but not their partners) of the car where they may have had their first cramped snog or shag, especially when accompanied by the right song from that era.

Witnessing violence between parents in the pre-school years increases aggressive behaviour in boys and depressive tendencies in girls at the age of 16 (Development and Psychopathology). This was true even after other causes of these problems - such as being directly abused or neglected, or witnessing violence in middle childhood - were taken into account in the sample of 155 children, followed from 18 months. Conclusion: if you must chuck the crockery at each other, do it when your kids have reached school.